This series started off well, I actually really enjoyed the super-human strength, family heritage story. I think the comedic/slapstick spin that the show put on it really helped to make the story flow, since we know it's nonsense, it was nice to see that the show knew itself that it was nonsense too and didn't take itself too seriously.
The two lead men in this show are SO HANDSOME. I can't even, honestly. I am more biased towards Ji Soo because he's more my cup of tea (or shot of soju if you will) than Min, but I seriously think both of them are terrific actors and super super good looking. They really did their jobs well.
Bong Soon is a cute girl, and she's a good actress, I just think her character got old really quickly trying to play out all the crazy subplots and twists that this show tried to stuff into the series. Maybe there were too many episodes, that's it. Probably could've taken away 5-8 episodes and closed it strong, but instead it sort of just dragged on with some more unbelievable antics.

All in all, good show, good looking, talented and believable cast (especially the overly-effeminate co-worker), I would recommend watching it if you're not looking for something too story driven, and if you like male eye candy.